Under Pressure (and Elephants)

Remember that post about how deep Alvin dives? Well, here’s a visual representation of how much pressure an object (like Alvin) would feel at 3870 meters (12,700 feet, or nearly 2.5 miles).

Scroll down for more info (and elephants):

This image is based on the average weight of the African forest and the Asian elephants.

At 3,780 meters under water, an object would feel roughly 5,600 pounds on every square inch of its surface. That equals the weight of roughly one elephant per square inch–or 13 elephants on just the area of my palm (18 square inches). Or 7,000 elephant across the entire surface area of Alvin (I really did not want to spend the whole cruise drawing 7,000 elephants, so you’ll just have to imagine that one). To withstand all those elephants (How do they get to the bottom of the ocean, anyway?), Alvin‘s personnel sphere is made of titanium. And at nearly three inches thick, it is built to withstand over 1.5 times the pressure it would experience on a dive to its maximum rated depth of 6,500 meters.

Ok, so why all the numbers? Well, from a structural standpoint, we humans have to calculate the load-bearing thresholds for lots of things that we build, and that we rely on every day: bridges, buildings, ships . . . submersibles. Understanding how forces act on materials, whether it’s pressure, gravity, temperature, or wind speed, affects how they’re made and what they’re made of–which often affects their cost. In fact, the single most expensive component on Alvin? You guessed it, the personnel sphere.

Note: No elephants (or cartoonists) were harmed in the making of this blog post.

About this expedition: Popping rocks revisited

We will be using the research vessel Atlantis, the submersible Alvin, and the autonomous underwater vehicle Sentry, to find and collect samples of “popping rocks”—basaltic seafloor lavas that contain large amounts of carbon dioxide and other gases trapped in high-pressure bubbles that pop when the rocks are brought to the surface. We intend to use these rocks to understanding the composition and origin of gases in the deep earth. This project began with an expedition in 2016 that was cut short due to mechanical problems. You can still see blog posts from the first trip here, and we will continue adding to them during the 2018 expedition.